import sys

n = input()
w = list(map(int, input().split()))
if sum(w) % 2 == 1:
    print("impossible")

    sys.exit()

w_div2 = sum(w) // 2
dp = [[0] * (w_div2 + 1) for i in range(len(w) + 1)]

for i in range(1, len(w)):
    for j in range(w_div2 + 1):
        if w[i - 1] <= j:
            dp[i][j] = max(dp[i - 1][j], dp[i - 1][j - w[i - 1]] + w[i - 1])
        else:
            dp[i][j] = dp[i - 1][j]

        if dp[i][j] == w_div2:
            print("possible")
            sys.exit()
print("impossible")